I've read that it's great for lactofermentation (like for pickling) and that's something I plan on trying the next time I have some.  In the past, I'd just pour it at the base of my tomato plants.  Prior to doing that, I often had issues with blossom end rot on my heirloom tomatoes, but once I started giving them a drink of whey, that issue went a-whey. 

If the tomato you used in the "knife restoration/maintenance" video is any indication, the whey cocktail is doing a great job on the tomatoes! ("Went a-whey."  LOL.  You funny!!)  I may use it in some baking this weekend (Keto Upgrade's cheese danish is delish!) and will research lactofermentation.  I have zero experience with it.